Radio propagation model

A radio propagation model, also known as the "Radio Wave Propagation Model" or the "Radio Frequency Propagation Model", is an empirical mathematical formulation for the characterization of radio wave propagation as a function of frequency, distance and other conditions. A single model is usually developed to predict the behavior of propagation for all similar links under similar constraints. Created with the goal of formalizing the way radio waves are propagated from one place to another, such models typically predict the path loss along a link or the effective coverage area of a transmitter.

Characteristics

As the path loss encountered along any radio link serves as the dominant factor for characterization of propagation for the link, radio propagation models typically focus on realization of the path loss with the auxiliary task of predicting the area of coverage for a transmitter or modeling the distribution of signals over different regions.

Because each individual telecommunication link has to encounter different terrain, path, obstructions, atmospheric conditions and other phenomena, it is intractable to formulate the exact loss for all telecommunication systems in a single mathematical equation. As a result, different models exist for different types of radio links under different conditions. The models rely on computing the median path loss for a link under a certain probability that the considered conditions will occur.

Development methodology

Radio propagation models are empirical in nature, which means, they are developed based on large collections of data collected for the specific scenario. For any model, the collection of data has to be sufficiently large to provide enough likeliness (or enough scope) to all kind of situations that can happen in that specific scenario. Like all empirical models, radio propagation models do not point out the exact behavior of a link, rather, they predict the most likely behavior the link may exhibit under the specified conditions.

Variations

Different models have been developed to meet the needs of realizing the propagation behavior in different conditions. Types of models for radio propagation include:

* Models for indoor applications
* Models for outdoor applications
** Ground wave propagation models
**Sky wave propagation models
**Environmental Attenuation models
**Point-to-Point propagation models
**Terrain models
**City Models

Models for outdoor attenuations

*Near-earth propagation models
**Foliage models
*** Weissberger's modified exponential decay model
***Early ITU model
***Updated ITU model
****One woodland terminal model
****Single vegetative obstruction model
**Terrain models
***Egli model
***Longley–Rice model
***ITU Terrain model
**City models
***Young model
***Okumura model
***Hata model for urban areas
***Hata model for suburban areas
***Hata model for open areas
***Cost 231 Model
***Area-to-area Lee model
***Point-to-point Lee model

Models for indoor attenuations

*ITU model for indoor attenuation
*Log-distance path loss model

Models for environmental effects

* Rain attenuation model
**ITU rain attenuation model
**ITU rain attenuation model for satellites
**Crane global model
**Crane two-component model
**Crane
**Crane model for satellite paths
**DAH model

See also

* Radio propagation
* Nakagami fading

External links

* [http://www.vtsociety.org/ IEEE Vehicular Technology Society - Propagation Committee]
* [http://www.atdi.com ATDI]
* [http://www.siradel.com Siradel]
* [http://flattop.its.bldrdoc.gov/itm.html Irregular Terrain Model (Longley-Rice)]
* [http://www.cpar.qinetiq.com/crumpet.html QinetiQ CRUMPET]
* [http://www.cplus.org/rmw/english1.html Radio Mobile]
* [http://deserthail.com RadioWORKS -- A freeware program for calculating radio wave propagation, path loss, and frequency information]

The following external references provide practical examples of radio propagation concepts as demonstrated using software built on the VOACAP model.

* [http://hfradio.org/ace-hf/ace-hf-demystified.html High Frequency radio propagation de-mystified.]
* [http://hfradio.org/ace-hf/ace-hf-reciprocal.html Is High Frequency radio propagation reciprocal?]
* [http://hfradio.org/ace-hf/ace-hf-noise.html How does noise affect radio signals?]